[Radioroslyn]

Ok try disconnecting one end of 30 4.7K resistor.

[Radioroslyn]

So what we are doing is disconnecting the hv to various stages to try and find where this noise is coming from. Seems like the osc is ok so it's on to the mixer (resistor 30) if that makes the noise go away there's a good chance the mica cap in the ift is bad but we'll see.

[madsowry]

I assume you wanted 28 reconnected before I separated one end of 30.  So that's what I did and the static is back.

[Radioroslyn]

So we are back to the XXL/osc circuit. Try replacing 26.
28, 26, and 25 are the key players in terms of what could causing noises everything else in that circuit (short of a bad socket) requires the tube to be in the socket and working to make noise. You posted previously that it makes the noise even if the XXL is out.

[madsowry]

OK  I replaced all 3 parts 25,26,and 28.  Still have the noise and yes if I take the Osc XXL out the noise is still there just not as loud.

Thanks for everything Terry.  I gotta go now.  Be back on Fri. morn.

Thanks again

Dick

[madsowry]

Hi Everyone 

         Back at this 41-280, finally.  As I was checking everything again I found what I thought was an open in part 37(3rd IF trans.).  I removed it and did not find any open but from the print I see mica caps 37B and 37C.   After testing the IF can some more these 100pf caps are measuring 37B-220 and 37C-265.  So they are out of tolerance but where are they?  I'm measuring across the black and green wires in the IF can for 37B and across the black and blue wires for 37C.  I know its probably a stupid question but I just don't see them anywhere else in the chassis.  I see and checked 37E which is on 2 pins of the 7C6 tube and the compensator is 37D and 37A checks out good.  I just don't know where those 2 mica caps are.  Thanks for any help!!!

Dick

[KCMike]

They are probably inside the IF can. Looks like its the second IF. You will need to remove the transformer from the can to get to them. Usually there is a dotted line on the schematics around the transformers that shows what's inside.

[Radioroslyn]

Hi Dick,
My acid test for IF transformers is do the trimmer peak when align. If not I'll dig in and see what's going on. Think I remember Ron posting that those two caps 100mmfd are built into the ceramic so they are unserviceable. In terms of values it not very critical they are used as a rf filter as apposed to being part of the tuned circuit.

[madsowry]

Thanks Mike and Terry.    I guess that's why I can't find them.  I have the trans out of the can so the only thing I can do is -while its out- clean the mica slice under the compensator and replace the old rubber wiring.
     Well it's good news and bad news.  Good that I don't have an open in the trans. and the caps are in the ceramic so that's why I didn't see them and Bad because I thought I found the noisy static problem.  Oh well tomorrow I'll put things back together and keep looking.  Thanks again

Dick

[madsowry]

Well I decided to really get into it.  I labeled everything and took the band switch out.  Cleaned all the contacts and rewired to get rid of the old rubber wire.  Looks a lot better.  Powered her back up and she STILL HAS THIS NASTY NOISY STATIC.  I thought we had it narrowed down to the osc.area and the A wafer of the band switch.  But after taking all that apart and cleaning and rewiring and resoldering, it's still there. Maybe a longer antenna would be in order. Right now I have an active antenna wired with coax to my bench but that doesn't seem to make any difference.

Any thoughts where to look next would be appreciated.  Thanks.

Dick

[KCMike]

Well just a thought, I've read thru the complete posts on this one and did not notice if you have checked for noise coming from something in your shop. Did you by chance try shutting off lights, computer, etc. Maybe try a different circuit to plug radio into. Good luck I'm interested in you finding the problem.

[madsowry]

Thanks Mike    When I bought this radio the seller had 2 of them.  One was in real good shape and the other was missing some veneer and the dial framework had been mangled.  So I bought both.  I was trying to get the one in good shape to work but that's the one with all the static.  So for the H**l of it I replaced the ecaps and installed some safety caps in the one missing the dial-powered it up and the radio came on booming and no static.  So I changed all the caps and cleaned it up and I'll use this one in the cabinet.  

   I'm still confused as to why that other one had so much static.  I did take it away from my bench to another room but it still had static.


    Dick